From Glossary of Meteorology
The physics of the earth and its environment, that is, earth, air, and (by extension) space.
Classically, geophysics is concerned with the nature of the physical occurrences at and below the surface of the earth including, therefore, geology, oceanography, geodesy, seismology, hydrology, etc. The trend is to extend the scope of geophysics to include meteorology, geomagnetism, astrophysics, and other sciences concerned with the physical nature of the universe. Geophysics uses analytical and mathematical, rather than purely descriptive, techniques.